More relevantly, nothing stops you from creating a tradeable note that says "redeemable for 1 bitcoin from <trusted authority>" and then using those as currency.
This happened with gold, and also would happen if we saw a true bitcoin bank rather than bitcoin wallet -- they'd pay a bit of interest, and in return would pool their deposits and use some fraction of them to generate revenue through other channels.
This happened with gold, and also would happen if we saw a true bitcoin bank rather than bitcoin wallet -- they'd pay a bit of interest, and in return would pool their deposits and use some fraction of them to generate revenue through other channels.